Do you use Qt5 or Qt4?

Qt5.

It is QT += quick1 then, not QT += quick.

If I only write Qt += quick1 in the .pro File, then QDeclarativeView works.
But the I get an Error by using QtQuick 2.0.

plugin cannot be loaded for module “QtQuick”: Unknown error import QtQuick 2.0.

Don’t use QDeclarativeView if you need to load QtQuick 2.0 components. Use QQuickView. Why do you think you need to use QDeclarativeView, out of interest?

I need QDeclarativeView because of performance.

I use Qt 5 on Ubuntu with VMware Player and when i start the application with QDeclarativeView then everything is okay.
When I use QQuickView it works but the application is very slow.

Ah, I see. QtQuick2 requires opengl, and doesn’t directly use a software rasteriser. I imagine that VMware Player provides opengl support via a software pipeline with greatly reduced performance, which could result in the performance problems you are seeing. I’m not 100% certain, of course.